NTSB Safety Recommendation P-70-035

NTSB safety recommendation P-70-035.

THE NTSB RECOMMENDS THAT ALL STATES, THE DISTRICT OF COLUMBIA, AND PUERTO RICO TAKE THE FOLLOWING ACTIONS: REVIEW THE REGULATOR DESIGN, MAINTENANCE, AND TESTING PROCEDURES OF THE GAS UTILITIES UNDER STATE JURISDICTION TO DETERMINE WHETHER ALL GAS CONSUMERS WILL BE PROPERLY PROTECTED AGAINST OVERPRESSURIZATION IN THE EVENT OF A MALFUNCTION OF A PRIMARY REGULATOR.

Priority: CLASS II

Overall Status: Closed--No Longer Applicable

Issued Date: 1970-10-14

Adopted Date: 1970-10-14

Overall Date Closed: 1976-07-20

Synopsis: ON NOVEMBER 6, 1969, DURING A HIGHWAY CONSTRUCTION PROJECT IN BURLINGTON, IOWA, A BULLDOZER WEIGHING 70,000 POUNDS DROVE OVER AND PARTIALLY COLLAPSED THE STEEL COVERS OF A GAS REGULATOR PIT, DAMAGING THE REGULATOR. WHILE THE PRESSURE WAS PARTIALLY CONTROLLED BY A MONITORING OR SAFETY REGULATOR, GAS, REPORTEDLY AT FOUR TO FIVE TIMES THE NORMAL OPERATING PRESSURE, ENTERED THE DISTRIBUTION SYSTEM. GAS CUSTOMERS IN THE AFFECTED AREA STARTED REPORTING HIGH GAS PILOTS AND FIRES TO ISU AND THE FIRE DEPARTMENT. THE HIGH-PRESSURE GAS SOURCE WAS TURNED OFF BUT FIRES CONTINUED TO BE REPORTED, THE FIRES WROUGHT MAJOR DAMAGE TO THE INTERIORS OF 10 HOUSES AND MINOR DAMAGE TO KITCHENS AND APPLIANCES IN 42 OTHERS. PROPERTY DAMAGE WAS ESTIMATED AT $80,000.

Probable Cause: The probable cause of the fires in the houses was the continued overpressure condition of the low-pressure distributions system for an extended period of time, which allowed pressure to build up until high gas flames ignited nearby objects. The initiation of the overpressure was caused by a bulldozer which damaged the largest primary working regulator which, with other regulators, controlled the gas pressure entering the low-pressure systems; and by inadequate performance of the monitoring regulator which failed to operate to limit the gas pressure to a safe level.

Ntsbnumber: DCA70MP001

Report Number: PAR-70-01

Addressee Name: State of Wyoming

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of West Virginia

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of Washington

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: Commonwealth of Virginia

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of Vermont

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of Utah

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of Texas

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of Tennessee

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of South Dakota

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of South Carolina

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of Rhode Island

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: Commonwealth of Pennsylvania

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of Oregon

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of Oklahoma

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of Ohio

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of North Dakota

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of North Carolina

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of New York

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of New Mexico

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of New Jersey

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of New Hampshire

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of Nevada

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of Nebraska

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of Montana

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of Missouri

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of Mississippi

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of Minnesota

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of Michigan

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: Commonwealth of Massachusetts

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of Maryland

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of Maine

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of Louisiana

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: Commonwealth of Kentucky

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of Kansas

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of Iowa

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of Indiana

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of Illinois

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of Idaho

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of Hawaii

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of Georgia

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of Florida

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of Delaware

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of Connecticut

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of Colorado

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of California

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of Arkansas

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of Arizona

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of Alaska

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: State of Alabama

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: Commonwealth of Puerto Rico

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20

Addressee Name: District of Columbia

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-07-20